Check out BCS Automotive. They're listed in sticky/1M exhaust clips.
The valves in their system operate same way but through boost level instead of electronics and you definitely get axtra roar when you put your foot down.

The Akrapovic may not be cheap, but I guarantee you once you take a listen to just the quality of sound produced along with fit and finish, not to mention materials used the money is there. Im basing this on the current Akrapovic Prices not the prices from Jan 1 2012 on forward.

I personally don't think that Akra sound that much better than some of the options that also have the "race" version. That is based on videos not IRL. But assume most people have never heard all options IRL so hard to have a reliable opinion without that. If Akra went no titanium and lowered the price like 40% I would be interested.